Demonstration of GaN-Based Solar Cells With GaN/InGaN Superlattice Absorption Layers

In this letter, we display InGaN/GaN-based photovoltaic (PV) devices with active layers in absorbing the solar spectrum around blue regions. The GaN/In_0.25Ga_0.75 N superlattice layers grown by metalorganic vapor-phase epitaxy are designed as the absorption layers with the same total thickness. The PV effect is almost absent when the In_0.25Ga_0.75N single layer is used as the absorption layer. This could be due to the large leakage current caused by the poor material quality and the relatively small shunt resistance. Devices with superlattice structure illuminated under a one-sun air-mass 1.5-G condition exhibit an open-circuit voltage of around 1.4 V and a short-circuit current density of around 0.8 mA/cm² corresponding to a conversion efficiency of around 0.58%.